Page 1
1
EDSGN 100: Introduction to Engineering Design
Section 10 Team 6
FOLDING SHOPPING CART
Submitted by: Kevin Chacha, Ugonna Onyeukwu, Patrick Thornton, Brian Hughes
Submitted to: Xinli Wu
October 28, 2013 http://www.personal.psu.edu/pmt5086/edsgn100_fall13_section10_team6_dp1.pdf
Page 2
1
Table of Contents
Cover Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Kevin Chacha
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Kevin Chacha
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Kevin Chacha
Description of the Design Task . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Brian Hughes
Design Approach . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 3
Brian Hughes
The Final Design approach and its Prototype . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Patrick Thornton
Engineering Analysis and Cost analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Patrick Thornton
Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Ugonna Onyeukwu
Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Ugonna Onyeukwu
Page 3
1
Abstract
Our team designed a folding shopping-cart to solve the burden of bringing groceries into an apartment
without an elevator or assistance. Through seven weeks of design, it can be concluded that our team designed a
folding shopping that is innovative, simple, and effective for people who need assistance with groceries.
Introduction
Our team was given the task of creating a folding shopping cart that would help individuals who live in
an apartment or in a house with carrying their groceries in an easier, simpler way. Our team collected
information through survey and other resources to help gather as much information as possible to help
create a device that would be of maximum use to the customer. Our team spent many hours brainstorming
ideas to create the best device that would help the public. Our team finally decided on an idea that would
help customers in every aspect. This device helps carry a large amount of groceries into an apartment or
house while also being able to be mobile through stairs and flat surfaces. The innovative wheels can assist
customers with stairs. A tri-wheel design was chosen to help carry groceries up stairs. Also the wheels are
able to move on flat surfaces. The innovative designs on this device help provide a reliable, simple device that
customers in need will be satisfied to own.
Page 4
2
Description of the Design Task
I. Problem Statement:
Too many people are unable to transfer their groceries from their car to their place of residence.
II. Mission Statement:
Our mission is to build a device that will fold into a shopping cart, and can easily fold back into
a compact design. A special wheel design will be implemented on the cart to aid those who have
trouble with stairs.
III. Design Specifications:
This product will be designed to be lightweight, foldable, and very versatile so that it will be
easy to use yet very helpful. The cart will be able to hold at least one hundred pounds, not sacrificing
durability for functionality.
Page 5
3
Design Approach
1. Gantt Chart
2. Customer Needs Assessment
What is the average weight of groceries you get per shopping run?
Would a folding shopping cart be of use to you?
Do you encounter any elevators/stairs to get to your place of residence?
How long would it ordinarily take to unload your groceries?
Are your groceries usually fragile or heavy?
Do you have a lot of storage space?
What would you be willing to pay for a folding shopping cart?
Our general consensus was that this product would only be useful for the elderly/disabled. The majority of
them live in either their family’s place of residence or in elderly housing, where they typically encounter either
stairs or elevators. Most of the time their groceries are relatively light and space is usually not an issue for
storing the cart. The surveyed audience stated that it generally takes them around 20-30 minutes to unload their
groceries, and they are forced to take multiple trips between their residence and their vehicle. The majority of
their groceries are not fragile, however occasionally they will have eggs or bread. The price range people are
willing to pay is around $30-50.
Folding shopping cart 9-Sep
16-
Sep
23-
Sep
30-
Sep 7-Oct
14-
Oct
21-
Oct
28-
Oct
Problem statement
Mission statement
customer need assessment
Gantt chart
Design approach
working drawing
prototype
working mechanism
engineering analysis
cost analysis
conclusion
formal write up
Page 6
4
3. Concept Generation
We began with the tri-wheel design because we knew we wanted this design from the start. We designed this
wheel with respect to the normal height of stairs, and the wheel is drawn to actual size.
Page 7
5
4. Design Selection Matrices
Square
Cart
Triangle
Cart
Bag
Cart
Motorized Stair
Climber
Tread
Climber
Ease of
Manufacture + 0 + - -
Cost + 0 + - -
Stability + + - + 0
Stair Climbing
Ability + + + + +
Folding
Ability + 0 + 0 +
Capacity + 0 + + +
Mobility + + + + +
Ease of Use + + 0 + 0
Net Total 8 4 5 3 2
Ranking 1 3 2 4 5
Chart 4.1- Plus/Minus Chart
Chart 4.2- Concept Selection Chart
Selection Criteria
Weight
(%)
concepts
A: Square Cart B: triangle Cart C: Bag Cart
Rating
Weighted
Score Rating
Weighted
score Rating
Weighted
score
Ease of
manufacture 15% 3 0.45 3 0.45 5 0.75
Cost 15% 4 0.6 4 0.6 5 0.75
Stability 10% 4.5 0.45 3.5 0.35 2 0.2
Stair Climbing
ability 15% 4 0.6 3.5 0.525 2 0.3
folding ability 10% 4.5 0.45 2 0.2 5 0.5
capacity 10% 5 0.5 3 0.3 5 0.5
mobility 10% 4 0.4 5 0.5 3 0.3
ease of use 15% 4 0.6 4 0.6 4 0.6
Total score
4.05
3.525
3.9
Rank
1
3
2
Continue?
Yes
No
No
Page 8
6
5. Design Approach
After narrowing our design to the square cart, we decided to focus on the dimensions of our tri-wheel
design, ensuring that it would effectively improve the stair climbing ability of our cart. We focused on keeping
the motion path of the axel perpendicular to the plane of the stairs; this will ensure a smooth and easy transition
up stairs. The axel and support struts are all hollow to maximize cost and weight savings.
Page 9
7
6. Working drawings
This is a CAD rendering of our cart in the unfolded and folded positions.
Page 10
8
7. Prototype
The prototype was built out of cardboard and wood, so it cannot hold the specified 100Lbs. However,
the cardboard mock-up does serve well to communicate the essence of our design. The scale of the prototype is
1:1 so it is the same physical size as our design and also folds just as the final design will. The prototype’s tri-
wheels are made out of wood, so they function just as the actual wheels will. We tested the wheel design on the
stairs and they performed tremendously.
Page 11
9
8. Working mechanism and engineering analysis
-Folding:
Our cart features a folding basket and a tri-wheel design to allow for easy storage and the ability to
climb stairs. The basket folds by simply lifting up on the outer edge of the basket. This design takes
advantage of parallel supports and other geometrical features to compress to a fraction of its original
size.
-Use:
The cart is to be unfolded and filled with groceries. The cart is then tilted backwards, such that the front
legs are no longer in contact with the ground. It can then be pulled, like a suitcase, to its final
destination. To use the cart on stairs, simply approach the stairs head on and drag the cart behind. The
wheels will adjust to the stairs and allow for an easy assent, with most of the weight of the groceries
supported by the normal force of the stair between each step transition. This will allow for resting
midway up the stairs for the less able clients.
-Engineering analysis:
When the basket is open, the top arm of the basket rests on the horizontal crossbeam to keep the cart
from opening further than it is designed. The stability of the cart is superior, it is currently designed to
carry 100Lbs, which is much more than would fulfill the customer needs. If this tenant of the design
prompt were changed, the excess structural integrity could be exchanged for cost and weight savings.
Page 12
10
9. Cost analysis
Our design uses both aluminum and Abs plastic to achieve a lightweight and cost efficient shopping
cart. The axel and bolts will consist of aluminum alloy 6061, which we can source for $1.11/Lb. , likely to
become cheaper if we purchase larger quantities. The cost of the aluminum parts is $10.35/Cart but this
number could be reduced if we used already manufactured bolts for the joints. The remaining parts of the cart
would be made using Abs Plastic resin and injection molding. Using the mass properties tool on SolidWorks to
determine the volume of the plastic parts, we determined that the plastic components would cost $45.25 plus a
one-time tooling cost to make the injection molds. Overall, the material cost of the cart amounts to $55.60.
This number could be lowered by subtracting some of the support pieces in the basket area. The design prompt
states 100Lbs of groceries, but this number is not realistic for people who are currently unable to carry their
groceries to their home. If this restriction were removed, our design could be altered to more accurately
address the problem. We would then be able to trade some excess stability for cost and weight savings.
Page 13
11
Conclusion
This report introduced a design to a cost effective and lightweight shopping cart. Our group found that
using a folding design would lead to easier accessibility and less storage space needed when the cart is not in
use. The tri-wheel feature helps to move the cart and its contents up stairs when needed. The materials that are
used to build this shopping cart lead to cheap and lightweight shopping cart also. These were the main points
that were given to our group when we surveyed people before the beginning of the design process.
Acknowledgements
We thank those who were apart of the surveying process.
We want to extend appreciation to Professor Xinli Wu Ph.D., P.E for allowing us to take apart in this
design and construction
We would like to thank the Penn State model shop and its operators for allowing us to construct a
working prototype of our design